Etherchannel Mode
active     Enable LACP unconditionally
auto        Enable Pagp only if a Pagp device is detected
desirable Enable Pagp uncondiationnaly
on           Enable Etherchannel only
passive   Enable LACP only if a device is detected

Configuration Example :negotiation_modes

Config#interface range fastEthernet X/X -X
Config-if#channel-group 1 mode on
Config-if#no shutdown
Config-if#switchport mode trunk
Config-if#interface Port-channel 1
Config-if#switchport trunk encapsulation dot1q
Config-if#switchport mode trunck

Etherchannel Protocols LACP and Papg

Both PAgP and LACP support up to eight active links between devices in a negotiated channel. LACP allows a maximum of 16 ports to be configured in a channel, but only eight can be active at any given time. Non-active links in an LACP bundle are placed in hot standby mode, and if any active link becomes inactive, one of the hot standby links will change to active mode and take its place in the channel

LACP uses the port priority and port ID values to determine which hot standby port will become active. The LACP port priority is set to 32768 by default for all interfaces; however, you can change this value to specify which hot standby links become active first. A lower LACP priority value will place an interface ahead of others when active ports are being selected. If hot standby ports are configured with the same LACP port priority, ports with lower port numbers will be selected first.

All ports in an EtherChannel must be configured to use the same protocol: either PAgP or LACP, not both

When you make a change to a port-channel interface, the changes are implemented on all physical interfaces. Conversely, if you make a configuration change on a physical interface that is part of the channel group, the change is not implemented on any of the other physical interfaces in the channel group or the group’s port-channel interface.

Cisco’s proprietary negotiation protocol before LACP is introduced and endorsed by IEEE.

Standards-based negotiation protocol, known as IEEE 802.1ax Link Aggregation Control Protocol, is simply a way to dynamically build an EtherChannel ( with or wihtout Cisco Products )

Configuration example

Config-if#channel-protocol “protocols”

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